In spite of the growth and development of the methods of soil walls stabilization of the excavated zone, the excavation and implementation retaining structures are one of the serious challenges for civil engineers in conditions, including in a) loose granular soils b) high groundwater level c) the existence of buildings and the passages overlooking the excavated zone d) the inefficiency and inadequacy of most of the methods for the soil wall stabilization for excavated zone with limited area and e) the high costs of conventional retaining structures. Hence, in some lands with a limited area that does not allow the use of bulky and heavy machinery or special methods of implementing the retaining structure, the stabilization of loose granular soil walls adheres to non-standard processes. Employing this type of process leads to financial losses for buildings, passageways and human casualties.
In general, to lower the groundwater level, two methods are used: (a) the implementation of the relief walls in excavated zone; and (b) the implementation of well points system in the boundaries of excavated zone. However, both methods are non-executable or not effective. Because, basically in submerged loose granular formations such as loose silty sand (SM), drilling and installation of concrete casing ring well with the required depth is hardly possible. Also, the level of the bottom of the well will raise decreasing the efficiency, and the presences of several relief wells in the excavated zone prevent any embankment operations and soil compaction.
However, the low depths of these wells lead to an increase in groundwater levels in the lower part of soil walls and their instability. The drainage well points system, despite having the effective performance of lowering the groundwater level, is not feasible due to (a) the lack of space on the top of excavation, (b) the existence intermediate hard layers in the range of effective depth.
On the other hand, in loose granular soils with high groundwater level, it is not possible for stepped excavation in range of 1-2 meters. Also, it is not possible to use and implement other methods of for soil walls stabilization in urban lands with limited areas such as; diaphragm walls, truss structures, sheet pile structures, piles, soil-cement columns and etc. Therefore, excavation and implementation of retaining structures in the conditions of loose granular soils and high groundwater level in urban plaques is still a serious challenge for most companies and civil engineers.
Existing prior art lack the ability to provide a system and method for constructing a retaining wall structure and a well point in granular soils under groundwater level. Thus, there is a need for a composite system and method for providing retaining wall structure and well points net with multi-stage construction process which is responsible to the drainage of the excavated zone and the stabilization of the soil slope wall, especially in urban lands with limited area and granular soils and with high groundwater level during the construction process.